Biology & Control of Canada Thistle (Cirsium arvense) in Michigan Christmas Tree Production
July 12, 2022 - Author: Debalina Saha, Assistant Professor Ornamentals and Christmas tree weed management, MSU Department of Horticulture
Canada thistle (Cirsium arvense) is a native of Europe that was most likely brought to North America with agricultural seed shipments in the 1600s (Minnesota Department of Agriculture [MDA], 2021). Today this rhizomatous and perennial weed is broadly distributed throughout the United States and Canada. It is a member of the Asteraceae (or Aster) family, which is one of the largest plant families with more than 24,000 member species. Other weeds in this family include bull thistle (Cirsium vulgare), dandelion (Taraxacum officinale), and common yarrow (Achillea millefolium) (Department of Crop and Soil Sciences, 2003–2021).
Canada thistle is a major problem in Michigan Christmas tree production. It spreads extremely quickly—10 ft–12 ft (3.0 m–3.6 m) in a single season—through its extensive root system and secondarily by seed (Washington State Noxious Weed Control Board, n.d.). This bulletin will help growers identify Canada thistle and develop management strategies for regulating it in their production systems.